Cellular 'Caps' May Boost Risk of Common Cold

Teensy caps at the ends of chromosomes may not only protect against aging, they may also reduce the risk of catching the common cold, a new study suggests.

The caps, known as telomeres, protect chromosomes from damage, and get shorter as we age. Previous studies have linked the length of telomeres with life span: Older adults with longer telomeres may have a decreased risk of dying during a given time period than people with shorter telomeres.

But the new study suggests that telomere length could play a more immediate role in the health of young to middle-age adults.

During the study, adults as young as 22 who had shorter telomeres were at an increased risk of catching the common cold compared to people with longer telomeres.

The findings are preliminary, but if they are confirmed by future studies, researchers might use telomeres as a marker for identifying people at increased risk for infections, said study researcher Denise Deverts, a researcher at Carnegie Mellon University in Pittsburgh.

Deverts and her colleagues measured the telomere length found on chromosomes inside the white blood cells (a type of immune cell) of 152 healthy people ages 18 to 55. Then, the individuals received nose drops containing the rhinovirus, a virus that causes the common cold, and were quarantined for five days to see if they became ill.

Sixty-nine percent of people who had been exposed to the rhinovirus became infected, meaning the virus found its way inside their cells but did not necessarily cause problems, and 22 percent actually developed cold symptoms.

Among those with the shortest telomere length, 26 percent developed a cold, compared to 13 percent of people with the longest telomeres, the researchers said.

The link between telomere length and the risk of infection was strongest for older people.

A cell's telomeres shorten each time it divides, and eventually, telomeres become so short that the cell stops working properly, and dies. This means that people with shorter telomeres inside their white blood cells may have an "older" immune system that is not able to respond as well to infection, Deverts said.

"Their immune systems are aging a little bit faster, and for that reason, they are more susceptible to the cold," Deverts said.

It's important to note that the study only found an association, and cannot prove that short telomeres were the reason that people got sick. Although the study took into account many factors that could affect a person's risk of catching a cold, including their age and body mass index, it's possible other factors could explain the link. For example, a genetic mutation could cause both shorter telomeres and an increased risk of infection, the researchers said.

The study will be published tomorrow (Feb. 20) in the Journal of the American Medical Association.

Pass it on: Shorter telomeres may increase the risk of catching the common cold.